What changed Trump's mind on bolting GOP?

Just last week, Donald Trump was once again hinting he'd be open to a third-party bid for the presidency. The brokered convention talk seemed sufficient to justify the threats.

Then Trump pledged at Tuesday night's debate, "I am totally committed to the Republican Party." He even expressed respect for his rivals for the GOP nomination.

A few days ago, Trump at the very least viewed an independent candidacy as important leverage over a GOP establishment he feared was moving against him. Now he's swearing off it. What changed?

First, whatever the Republican National Committee said to reassure Trump and Ben Carson that a contested convention wasn't a conspiracy against anti-establishment candidates — the RNC reportedly met with Trump's campaign — seems to have worked.